Process of treating hydrocarbon oil



June 30, 1931. J. D. SEGUY I PROCESS OF TREATING HYDROCARBON OIL FiledDec. 19, 1928 Patented June tidy-193i a. a rs m r a carter;

JEAN ID. SEG'FUY, OF cmcneo, ILLINOIS, ASSIGNOR T UNIVERSAL OIL PRODUCTS(701V!- EAINY, 9F CHICAGO, ILLINOIS, A CORPORATION 0F SOUTH DAKOTAPROCESS 0E TREATING HYDBGGARBON OIL Application filed December 19, 1928.Serial No. 327,004.

This invention relates to improvements in process of treatinghydrocarbon oil, and is more particularly directed to the cracking ofsuch hydrocarbon oils as petroleum for the production therefrom ofgasoline or other light hydrocarbons. I

This invention is more particularly directed to that type of crackingprocess in which the oil may be passed through a heatis ing tube, thento an expansion chamber, the

vapors removed and subjected to dephlegmation, and the reflux condensaterecracked. The residuum in such type of process is drawn out of theexpansion chamber.

In processes of this t e, particularly in handling heavy oils or 0t eroils tending to produce substantial quantities of coke and sludgedifiiculty may beexperienced in getting a high yield of gasoline and atthe same so time producing a marketable residuum.

The object of this invention is to obtain from the process a. desiredyield of gasoline, While at the same time limiting and possiblypreventing the formation of an objectionable amount of coke and sludgein said residuum.

To this end, the liquid products or residue separated from the vaporsare continuously withdrawn from the system in such a manner that theyremain in the reacting zone only for a minimum length of time, dependingupon the characteristics of the oil undergoing treatment, thus avoidingas far as possible, obj ectionable formation of coke, sludge, and thelike due to extended retention of this liquid residuum at hightemperature. The time limit during which the liquid residuum shouldremain in the expansion chamber at high temperature is dependent uponthe type of oil treated and the extent to which it iii is desired tolimit the formation of sludgeand coke and the like, and it iscontrolledby the height to which the residue is permitted to accumulate in theexpansion chamber and by the 'rate of withdrawal of said residuetherefrom. For a given time limit, this height is dependent upon thesize of the sep arating or expansion zone, the rate of feed of thematerial through the apparatus, and the pressures,.and temperaturesused.

59 As a further object of the invention, the

liquid residue is continuously withdrawn from the expansion orseparating zone at such a rate that it remains in said zone for thedesired length of time, and thereafter is immediately partially cooledas it is withdrawn from the zone and flashed under reduced pressure, andthe flashed vapors may be subable cooling agent, preferably the mixtureof hydrocarbon products from cracking which goes by the name of pressuredistillate bottoms and which, in a process of the character described,is a cut intermediate the reflux condensate and the end point gasolineproduced and which in the trade would correspond to heavy naphthakerosene fractions. This cut may cover a boiling point range betweenabout 400 and 600 F.', more or less.

The primary cooling by direct heat interchange and the subsequentcooling due to flashing, arrestany reaction that may tend to proceed inthe residual products after they are withdrawn from the high temperaturezone, thereby preventing the formation of objectionable amounts ofsludge and coke.

The temperature to which the residual products withdrawn from the hightemperature zone may be cooled by, controlled heat interchange beforebeing subjected to flashing, must be properly balanced with the degreeof reduction of pressure which they undergo during flashing, so as toproduce the desirable total cooling effect, as Well as the desireddegree of vaporization of the lighter portion of the residual productswithdrawn from the high temperature zone.

-Other features of the invention will be apparent from the followingdescription of the process according to the invention:

In the accompanying drawing, I show an apparatus suitable for carryingout the present invention, it being understood that this is merely adiagrammatic showing and in no sense drawn to scale.

Referring to the drawing, 1 designates a conventional typefurnace inwhich is mounted the heating tube 2, provided with a. trans:

tion zone fer line 3, having a throttle valve 4: and leadmg to thereaction or vapor separating or expansion chamber 5. The vaporsseparated therein pass out of the reaction chamber through line 6,having throttle valve 7 to the side of'the dephlegmator 8. From the topof the dephlegmator, the uncondensedvapors pass through line 9 tocondenser coil 10 and.

thence to receiver 11. This receiverhas gas control valve 12 anddistillate control valve 13 for the discharge of these respectivethrough-the draw-0H pipe 18 connected to the bottom of the chamber 5.,The rate of withdrawal is controlled in a suitable manner, dependingupon the conditions of the operation to maintain in chamber 5 suchliquid level as will provide for the desired time element during whichthe residual liquid products may remain in the high temperature zone 5without becoming laden with objectionable quantities of slud" e andcoke.

, Additional side draw-o s 18 are shown but should only be used afterbottom drawoif 18 has become clogged, although the latter draw-offshould be used, if possible, alone during the operation, particularlywhen the level which must be obtained in chamber 5 is relatively low.The residual liquid products withdrawn from chamber 5 through pipe l8 inwhich is interposed valve 19 are passed to 1ine'20, in which isinterposed valve 21 and into flash chamber 22.

As a feature of the invention, the residual liquid products from chamber5 "are mixed during their .passagefrom chamber 5 to flash chamber 22with a suitable quantity of socalled pressure distillate botto'ms,introduced into. line 20 through branch 23, controlled,by valve 24. I r

Before being introduced into the system, the supply of pressuredistillate bottoms may be brought to the desired temperature by eitherheating or, cooling by suitablemeans (not shown) so.that, by a propercontrol of the temperature and quantity of said pressure distillatebottoms introduced, the mixture of pressure distillate bottoms andresidual products from chamber 5 may be partially cooled to a suitabletemperature below the temperature at which objectionable extendedreaction proceeds' The temperature and amount of the pressure distillatebottoms introduced in line 20 depends not only upon the temperature towhich it isdesired to cool the un vaporized products from chamber 5,;butit also depends upon the characteristics of the products desired fromthe process, particularly upon the viscosity, flash and fire points,

and other characteristics which may be specified for the residuum to beproduced by the process.

At the same time as a supply of cooling agent, to wit :pressuredistillate bottoms, is introduced from line 23 into the residualproducts from chamber 5 and in direct physical contact therewith, anadditional reduction in temperature of these residual products isobtained by reduction of pressure, such as to cause flash distillationin chamber 22. This reduction of pressure may be effected by theregulation of either or both of the valves 19 or 21, depending uponwhether it is desired to introduce the pressure distillate bottoms before or after the pressure has been reduced on the unvaporized liquidproducts with which said pressure distillate bottoms are to be admix (1.

Partial vaporization of the mixture is effected in the flash chamber 22and the degree of vaporization is dependent upon the degreeof totalcooling due to the partial cooling resulting from the admixture ofpressure distillate bottoms and the partial cooling resulting'from thereduction in pressure.

The degree of vaporization in chamber 22 may also be controlled orhelped by introduction of steam orother heated gas into ghamber 22 or bymildly heating said cham- The unvaporized residue from phamber 22 iswithdrawn therefrom through line 25, controlled b valve 26, and thence"cooled, stored, or sent or further treatment. The vapors released in theflash chamber 22 may be passed through line 27, controlled by valve 28,condensed in condenser 29 and collected in receiver 30, or these vaporsmay b assed through branch 31, controlled by valve 32, and directed to adephlegmator 233 from which uncondensed-gvapors pass to line 27 throughbranch 34, controlled by valve 35, and from which condensate may bewithdrawn through line 36 and directed to storage. or taken by hot oilpump 37 and returned through line 38 into the dephlegmator 8 from whichit is returned to the system for further treatment.

Raw oil or other cooling medium, may be introduced to dephlegmators 8and 33 in a suitable manner.

The pressure distillate bottoms used in the process to partially coolthe unvaporized products from the cracking reaction before they aresubjected to'flashiug ma be a product of the same operation or o a(previous operation of the process, depen ing upon the degree offractionation to which the vapors produced in the process are subjectedbefore collection.

In-the method of carrying out the invensea tion illustrated in thedrawing, the pressure distillate bottoms introduced from line 23 willgenerally result from the re-distillation of the pressure distillatecollected in the receiver 13 after dephlegmation of the vapors indephlegmator 8. In general practice and in carrying out a process of thecharacter described, the vapors leaving the dephleg mator 8 have an endpoint higher than the end point of gasoline, and it is necessary tosubject these vapors after condensation and collection as pressuredistillate to distillation for separation of the gasoline. The res iduefrom such distillation, generally called pressure distillate bottoms, isthe product used as described in the process of this invention.

As another method to carry out the invention, the vapors leaving thedephlegmator, instead of being condensed and collected as such and aspressure distillate, may be subjected to additional de hlegmation in asecondary dephlegmator lhot shown) whereby said vapors are separatedwithout additional distillation into end point gasoline vapors andcondensed pressure distillate bot toms. The end point gasoline vaporsare then condensed and collected as shown, and the pressure distillatebottoms produced from said secondary dephlegmator may then be usedalone, or .in admixture with pressure distillate bottoms from othersources, to cool the unvaporized liquid products removed from chamber 5in the manner heretofore described.

When the process is carried out along the alternative method justdescribed, the pressure distillate bottom return line connecting thebottom of the secondary dephlegmator to the draw-oh? line 18 fromchamber 5 may comprise branches and bypass permitting the regulation ofthe amount of pressure distillate bottoms returned to the system throughline 23 and by-passes on which may be interposed coolers, heaters, andhot oil pumps to permit the control of the temperature at which thepressure distillate bottoms are to be admixed with the unvaporized liopuid products from chamber 5 and the pressure under which they are to becharged into the line 18.

In the event such a method is carried out where pressure distillatebottoms are produced in the process by means of a secondary dephlegmator(not shown) the condensate formed in dephlegmator 33, instead'ofI'Elllllll. ing to the dephlegmat/or 8, as shown in the drawing, may bereturned to the secondary deplil-egmator (not shown) in toto or in partto both the primary dephlegmator 8 and the secondary dephlegmator (notshown).

Among the advantages of the process herein described is the fact thatthe admixture of'the pressure distillate bottoms with the unvaporizedproducts from the high temperature cracking zone arrests rapidly anyextended cracking of said products, and that a relatively small quantityof pressure distillate bottoms is generally sufficient to produce arelatively large cooling on account of products from reaction chamber 5.This reduces the viscosity of these products, and it helps avoidingclogging oi the residuum draw-0d lines which may occur on account of thehigh viscosity of unvaporized products resulting from the treatment ofcertain oils, even though said products contain less than 2% sludge orthereabouts. In other words, depending upon the characteristics oi": theoil treated, the unvaporizcd products withdrawn from the chamber 5 andcontaining about 2% sludge or coke may have viscositics ranging from,say to 1000 seconds Saybolt .turol, even though the cracking reactionhas been limited to the extent that will produce about 2% sludge or lessin every case. r'ldminture of said unvaporized products with pressuredistillate bottoms produces the desired cooling efiect at the same timeas it reduces the viscosity.

As another advantage pressure distillate bottoms resulting fromprocesses of the character heretofore described, may contain some lightfractions which, if separated, might well come within the rant "e ofboiling points of gasoline fractions. Elie admixture of these pressuredistillate bottoms with the unvaporized products and the flashing of themixture thereafter permits vaporization. of such. portions of the pssure distillate'bot toms as are herein referred to and they are furtherrecovered after cooling and condensation.

inother advantage consists in that the ad mixture or" these pressuredistillate bottoms with the heavier unvaporizcd liquid products from thereaction tends to lower the vapor pressure of the products undergoingflashing, which results in a larger amount of distillate carried over-ata definite temperature, therefore resulting in an easier control of thedegree of vaporization in chamber 22, and overcoming, to some extent,the reduction in degree of vaporization resulting from reduction oftemperature due to the adminture of said pressure distillate bottomswith the residues from the chamber 5.

As an illustration of a method to carry out the invention, Californiaoil having a gravity of about 19 13-. may be heated in coil 2 to atemperature of about 900 F. under a pressure of about 150 pounds. Theunvaporized products are withdrawn from the chamber 5 at such a ratethat no more than about 65 to 85 cubic feet of liquid is permitted toaccumulate therein. These products withdrawn from chamber a 8 at atemperature of about 800 F. are cooled by admixture with about 10 to 3(of pressure distillate bottoms resulting in a partial cooling of themixture to a temperature of from 400 to 500 F after which the pressuremay be reduced from 150 pounds down to about 20 to 25 pounds, or less.a,

Distillation in the flash chamber 23 is so controlled by injection ofsteam that the viscosity of the residuum withdrawn from the bottomofsaid chamber 23 is maintained below 500 secqnds Saybolt furol, at 122F., j

and the flash point at about'150 F., with a coke and sludge content ofless than 2% measured by benzol centrifuge:

In this operation about 40 to 45% of 437 F. end point gasoline isproduced based on the charge, and about of the residuum, havingcharacteristics heretofore described, is 'withdrawnfrom the flashchamber 23.

I claim as my invention:

1. A process of cracking hydrocarbon oil, comprising subjectingthe oilto cracking temperature under pressure, thereafter separating the vaporsfrom non-vaporous residue, removing, condensing and collecting thevapors, removing the liquid residue from the cracking zone before itcontains objectionable amounts of sludge and ,coke, and admixing withsaid residue a quantity of pressure'distillate bottoms so controlled asto amount and temperature as to cool said residue to-below crackingtemperature, thereafter reducing the pressure on the mixture of residueand pressure distillate bottoms so as to cause partial vaporizationthereof and additional partial cooling.

2. A process of cracking hydrocarbon oil,

comprising subjecting the oil to cracking temperature undersuperatmospheric pressure, thereafter separating the vapors from liquidresidue, removing, condensing and collecting the vapors, removing) theliquid residue from the cracking zone fore it contains objectionableamounts of sludge and coke, admixing with said residue a controlledquantity of hydrocarbon oil distillate having a boiling point rangebetween approximatel 400 to 600 F., said distillate being in suc amountand of such temperature as to' cool said liquid residue to belowcracking temperature, thereafter reducing the pressure on the mixture ofresidue and said oil distillate so as to cause partial vaporization andaddi tional partial cooling.

In testimony whereof I afiix my signature. EAN D.

